Being an estranged father, Fundoshi is hard on Yukata outwardly. He has some internal conflict about fatherhood, but wants to raise his son to be an honorable man and, eventually, a powerful berzerker.
Though he grew up without his father, Yukata strives to be something Fundoshi can be proud of. His mother talked leagues about his father's power, and he always wanted to be the strong, honorable man she spoke him to be. He has insecurities about their relationship.
She wouldn't mind a headlock in between those sweet biceps. Her feelings are more complicated than they should be. She really, REALLY likes him, but doesn't want to be a burden to Fundoshi. She says that, but she's always all over Fundoshi, providing him with affection.